Method for making seamless flooring and the like

ABSTRACT

Coated substrates of much superior wear and stain resistance are formed by successively superimposing epoxy resin and at least three coatings of polyurethane each formed from diisocynate and branched chain polyols that are crosslinked by a polyhydroxy material, the outer coating being of different composition from inner coatings, and comprising a polycaprolactone chain extender. This invention relates to highly wear resistant and decorative seamless flooring which may be formed over various surfaces such as concrete, wood, vinyl asbestos tile, and the like, from a plurality of coats of liquid compositions. It particularly relates to the wear resistant glaze layers of a seamless flooring, and to a polyurethane base composition used for forming such layers.

United States Patent 1191 Evans et al.

[ Sept. 23, 1975 METHOD FOR MAKING SEAMLESS FLOORING AND-THE LIKE [73]Assignee: Isonetics Corporation, Rochester,

[22] Filed: July 11, 1972 [21] Appl. No.: 270,620

[52] US. Cl. 427/203; 427/407; 428/423 [51] Int. Cl. B05D 1/36; E04F15/10 [58] Field of Search 117/9, 16, 26, 31, 32,

117/33, 72, 161 KP, 161 ZB; 260/77.5 AM,

3,756,845 9/1973 Zasadny et a1 117/72 3,761,439 9/1973 Ward et a1.260/32.8 N

3,775,354 1l/1973 Hostettler et al. 260/2.5 AN

Primary Examiner-William D. Martin Assistant Examiner-Shrive P. BeckAttorney, Agent, or FirmBacon & Thomas [57] 7 ABSTRACT Coated substratesof much superior wear and stain resistance are formed by successivelysuperimposing epoxy resin and at least three coatings of polyurethaneeach formed from diisocynate and branched chain polyols that arecrosslinked by a polyhydroxy material, the outer coating being ofdifferent composition from inner coatings, and comprising apolycaprolactone chain extender, This invention relates to highly wearresistant and decorative seamless flooring which may be formed overvarious surfaces such as concrete, wood, vinyl asbestos tile, and thelike, from a plurality of coats of liquid compositions/1t particularlyrelates to the wear resistant glaze layers of a seamless flooring, andto a polyurethane base composition used for forming such layers.

14*Claims, N0 Drawings METHOD FOR MAKING SEAMLESS FLOORING AND THE LIKEBACKGROUND OF THE INVENTION Polyurethane compositions have been proposedfor and used in the preparation of seamless flooring for several years.In the year 1969, approximately 16 million gallons of clear urethaneglaze were used for this purpose, indicating a dollar volume of about100 million dollars. In 1971, however, the sales were only about 2 to 5million dollars, showing that the polyure thane glaze flooring astheretofore sold, did not meet expectations.

In the flooring as earlier used, a coating of moisture curingpolyurethane (about 40% solids) in a solvent such as xylene or othersolvent, was applied to the substrate to saturate it and provideadhesion. After the first coat had at least partially cured, a secondcoat was ap plied, and while the second coat was still wet, chips ofcolored dry paint were scattered over and pressed through the surface.When this layer had dried, the chips which had not adhered were sweptaway, the surface sanded and vacuumed, and another coat of clearurethane glass was applied thereover. While that coat was still wet,chips were again scattered over the surface, pressed therein, and whenthe coating had hardened, the floor was again swept and vacuumed, and afurther clear coat of urethane glass (40% solids) applied. As soon asthat coating had hardened, many more coats of 40% solids urethane glazewere applied thereover, each one after the former had hardened.

The flooring as thus produced had these drawbacks: The first coat didnot adhere satisfactorily to grade level concrete. It was a 40% urethaneglaze in hydrocarbon solvent and thus dissolved hydrocarbon solublestains which were invariably present on the floor, and these stainsmigrated through to the top of the flooring. Furthermore, the urethane-composition invariably turned brown after prolonged exposure toultraviolet light. Finally the many coats required a great deal oflabor, could not be applied in a single day, and the large quantities ofsolvent such as xylene caused considerable toxicity and odor.

Consequently, the industry evolved the following system: (l) A sealercoat was applied to keep out stains, give adhesion to any substrate, andbond to the next coat. This was either a 100%-solids epoxy or an epoxyemulsion. (2) A chip coat was developed to hold the chips, bridge cracksin the floor, and bond to the next coat. Ordinarily this was the same asthe sealer coat, (3) a chip-binding coat or intermediate coat wasapplied to bind the very hydrophilic chips to each other and to hardenthem up enough so that they could be sanded. In most cases one ormorecoats of a polyurethane glaze was used for this purpose, but in someinstances a polymeric latex or a clear epoxy emulsion was used. (4)Finally, glaze coats of curing polyurethane in solvent were applied toprovide the wearing surface and to give abrasion resistance, stainresistance, and leveling. For each of the coats, an obvious requirementis rapid cure. Without it the job would take too long to be practical.

While the multi-layer system thus proposed is much superior to theoriginal system, it still has many prob lems. When the epoxy emulsion or100% solids epoxy is used for both sealer and clip coats, it becomesbrittle, shrinks and cracks. This is permissible in a sealer coat,

but not a chip coat, which must bridge cracks. In addition, the curerate of the epoxies is very temperature dependent. Being two packagematerials, a material with a reasonably long pot life has aninordinately long cure time on a cold floor. Another problem peculiar tothe epoxies, when used in urethane systems, is purpling. This cause isnot well understood, but in a significant number .of cases the interfacebetween the epoxy and an-unpigmented urethane develops an unsightlypurple color.

While thecurrently available base and chip coats present problems, theyare more satisfactory than the currently available glazes which have thefollowing faults:

A. The very high xylene content is unsatisfactory for two reasons-thelarge amount of xylene is unpleasant and dangerous, and the solidscontent of the glaze is so low that several coats must be appliedleadingto high labor costs.

B. The glaze yellows badly because of the aromatic isocyanates used.Ultraviolet absorbs effectively haltyellowing only temporarilya fewmonths to a year-before the film yellows as much as if the absorber werenot there.

C. The film formed from the glaze abrades rather quickly.

The obvious solution to the high xylene content, to use less reduction,did not work: Bubbles formed, which eventually'broke and collected dirt.Apparently, reducing the xylene content permitted the surface skin toform. This stopped outward diffusion of carbon dioxide which, beingentrapped, formed bubbles.

A solution to the yellowing problem is the use of the non-yellowingaliphatic isocyanates. All of these have certain disadvantages. Forexample, hexamethylene diisocyanate is extremely expensive, is highlytoxic, and rather slow to cure. Hydrogenated MDI (HMDI) has twoisocyanate groups with equal reactivity. Consequently, it forms highlyviscous prepolymers which have a high percentage of free HMDI, which isextremely allergenic via skin absorption.

Isophorone disisocyanate, IPDI, a new material from Germany, seems to bethe best isocyanate available.,lt is the lowest-priced aliphaticdiisocyanate. Its two isocyanate groups are of unequal reactivity sothat it gives lower-viscosity prepolymers containing less free monomervisa-vis HMDI. However, IPDI has serious drawbacks: although less toxicthan HMDI or hexamethylene diisocyanate, it will still cause seriousharm via skin absorption. Clear film from IPDI prepolymers degrade toliquid in strong sunlight. Prepolymers formed from the more reactivealiphatic isocyanate group of IPDI are terminated by the less-reactivecycloaliphatic isocyanate groups which moisture cures slowly.

The abrasion resistance problem is probably the most serious. Abrasionresistance is the property which is sought by the purchaser or aseamless floor. None of the solutions mentioned above helped to improvethis property. The aliphatic isocyanates, rather than helping improveabrasion resistance, made it worse.

Floor surfaces, particularly those in public buildings, require not onlyabrasion resistance, but resistance to contamination or staining causedby tar or asphalt brought in by foot traffic from road or. parking lotsurface. To be a successful floor coating composition, the resultingcoating must adhere strongly to the base, must dry or cure bubble free,must produce in a single application a heavy coating that is highlyresistant to both abrasion and asphalt staining.

It is an object of the present invention to provide a laminated,seamless, polyurethane-base flooring that may be applied over asubstrate such as concrete, wood, or the like, which adheres strongly.bridges small cracks, is not stained by migration of staining materialsfrom the substrate, is stain resistant to asphalt, tars, and the like,has abrasion resistance superior to prior polyurethane-base floorings,is decorative, requires lower labor cost and less solvent than didurethane-base seamless floorings heretofore used, and which is free fromthe yellowing and deterioration caused by ultraviolet radiation.

It is another object of the present invention to provide apolyurethanebase coating composition of high solids content that may beapplied over a suitably prepared base to provide a glaze layer of highwear resistance that resists staining by asphalt to a much greaterextent then coatings previously proposed.

It is another object of the present invention to provide apolyurethanebase coating system that may be applied to suitably preparedvinyl, tile, vinyl asbestos tile, wood, and the like. This will providea clear, highly abrasion resistant coating which will not requireexpensive stripping and waxing.

It is a further object of the present invention to provide relativelylow cost polyurethane-base coating compositions of high solids contentwhich, although having excess of terminal-NCO groups, will have longterm viscosity stability when maintained in moisture free containers,yet after it is mixed with a suitable crosslinking polyol, will set upand dry in a very few hours without bubbling.

Other objects of the present invention will become apparent from thefollowing description of the invention.

THE INVENTION In accordance with the present invention, multi-layerseamless floors of exceptional quality are produced which, in mostlayers, comprise polyurethanes which are isphorone diisocyanate-polyolreaction products. Preferably all layers after the initial sealer coatthat is applied to the substrate comprise such polyurethanes, but thosein outer layers are of substantially different composition from those ofinner layers.

We have found that the character of the polyol, including its branching,its equivalent weight, the basic chemical makeup thereof, and the typeof alcohol groups, is of great importance in formulating the differentcoatings for the various layers of the flooring. Both polyol used in theprepolymer and that used as a chain extender can be varied. Furthermore,the separate polyurethane coatings such as those used for binding thepaint chips and those used for providing abrasion and stain resistancemust have a very different polyol composition in the prepolymer and/orchain extender. The separate coats are described in more detail below.

Sealer Coat The first coating applied to the substrate is the sealercoat. We have found this may be the same as that used formerly, namely apigmented commercial spray emulsion which is formed from two parts, onecontaining catalyst or curing agent such as amines in solvent, and theother, the resin curable with the curing agent. The

two parts are preferably both separately pigmented and are mixedtogetherjust prior to use. The resin is applied over the clean substrateand allowed to cure for a coupleof hours to a nearly tack-freecondition. Example 1 is an excellent sealer coat.

Example 1 Part A.

Using a high speed disperser, the pigments are premixed in water alongwith other components except resin. Then resin is mixed in. Thecomposition:

Part B.

Using a high-speed mixer the resin and proplyene glycol are mixed, thenalternate portions of No. 1 White and water are added, and finally theR-900, The composition:

Parts Versamid 5501* 152 Propylene glycol 50 No. 1 White 270 Water 513R-900 titanium dioxide 88 Equal volumes of Part A and Pan B an: mixedjust prior to use. *See Glossary in Appendix for composition of this andall subsequent trade names.

Chip Coat The second coating applied over the sealer coat is apolyurethanc chip coat. The function of the chip coat is to adhere tothe sealer coat and to the wear and stain resistant or outer coats, andalso to bond to, form a matrix for, and to reinforce the paint chipswhich provide the main design to the flooring.

The chip coat is preferably from a two pack material comprising a -NCOterminated prepolymer in one package and a crosslinking agent inanother. It must have both a sufficiently long gel time to permitspreading, chip holding, and a sufficiently short drying time to permitfurther coats to be applied. The prepolymer in the coating should alsohave sufficiently low viscosity to permit application of a high solidssolution, i.e. 60% or more solids, to give sufficient film build.

We have found that the polyol used in forming that main component of thechip coating should, for best results, be a branched chain material, forexample, a triol or tetrol of between 1000 and 2000 equivalent weightand preferably between 1 and 1500 equivalent weight. Such polyols arecomposed principally of propylene oxide units on a suitable branchingbase such as trimethlolpropane or pentaerythritol. Other polyols such asthose derived from tetramethylene oxide, ethylene oxide, and ethyleneoxide-propylene oxide block polymers are not excluded.

weights, proportioned to provide equivalent weightswithin the 1000 to2000 range so that the prepolymer with isocyanate and the resultantcurved film will have a distribution of intervals between urethane orurea groups. Thus superior properties are obtained with prepolymers of amixture of polyoxypropylenetriols (POPT), part of which mixturecomprises a trio] of 200 to 500 equivalent weight and part of whichmixture is a triol of 1100 to 2000 equivalent weight, the parts beingproportioned to provide a weight average equivalent weight of between1000 and 2000.

The polyol is reacted with an aliphatic isocyanate to produce aprepolymer. The reaction' is conducted under the standard conditions forsuch preparations. The diisocyanate should be one which has unequalreactivity of the two isocyanate groups. One such is hydrogenated2,4-tolylene diisocyanate. Another, and preferably, is IPDI.

The diisocyanate (lDPl) and polyols can be proportioned so that in theprepolymer for the chip coats there is about 1.5 to 2.5 times as many(preferably about twice as many) equivalents of isocyanate (NCO) asthere are total equivalents of polyol. The equivalent weights of polyolsare selected so that the total isocyanate utilized in the chip coat isnot in excess of one-third of the weightor prepolymer solids (total ofpolyols plus isocyanate), preferably about 20% or not in excess of 25%of the prepolymer-solids. The free unreacted-NCO in the prepolymershould be at least 1.5% but usually is less than 6% of the weightthereof, and about 2 to 4% is preferred with about 2% to 3% being aboutoptimum.

In the preparation. of. the prepolymer the isocyanate is mixed with asuitable solvent such asxyleneor other suitable solvent or solventmixture that is free of functional groups that would react with theisocyanate, and

I a small amount such as 0.1 to- 0.25 part of a catalyst which ispreferably a dialkyl tin salt of a long chain fatty acid such asdibutyltin'dilaurate. These materials are put into' a closed reactorsuitably equipped for stirring and for maintaining temperature ofdesired value. Moisture is excluded with a blanket or dry nitrogen. Tomaterials in the reactor is added' the polyol or polyol mixture, usuallya trio] of about'200 to 300 equivalent weight mixed with a tr'iolofabout 1200 to 2000 equivalent weight, the mixture being proportioned asabove described. The materials are usually c'ooked at about 150 to 200 Fduring and from a few minutes to 2 hours after the addition of thetriols. The resulting prepolymers are preferably about 80% solidsinsolution of xylene or other suitable hydrocarbon solvent.

EXAMPLE 2 A prepolymer for use in a chip coat prepared by adding amixture of Parts LHT-240 (0.2l equivalent) 5] ,LHT-42 (0.82 equivalent)416 to the following maintained at 160 F under a blanket of drynitrogen:

' Xylene The materials are then-cooked from a few minutes to 2.5 hoursto complete reaction.

The chip coat is made by dispersing in a prepolymer pigments, bothhiding and inert; viscosity stabilizers such as benzoyl chloride, borontrifluoride etheratc, or acetic anhydride, and suspending agents such asasbestos fiber and/or hydrogenated castor oil. Additional I solvent isgenerally needed. The mixture is ground in a 'pebble mill in thepresence of a dry nitrogen atmo-.

sphere until it reaches a suitable fineness of grind. Example 3 is apreferred material.

EXAMPLE 3 A chip coat is prepared by grinding all together in a pebblemill under a blanket of dry nitrogen the following:

Parts Prepolyrner of Example 2 25 I0 R-900 titanium dioxide 577 No. 1White 2450 71105 asbestos fiber 43 Benzoyl chloride 6 lPDl 60 Xylene 360MFA-60 (pigment wetting agent) l6 The materials are ground to thedesired fineness of grind. If necessary more xylene is ground in to give100 Krebs units viscosity. Finally Dibutyltin dilaurate I 3 is mixed in.v v

Since example 3 'requi'res'l4 hours to cure with atmospheric moisture,we have found a crosslinking agent of particular type must be added tosuitably shorten 'the drying time.

The normally used crosslinking agents, such as glycerol and lowmolecular weight triols, have been found to be unsuitable betweenthey'give, typically, dry times as long as moisture cure. We have foundthat resinous solids, having four or'more hydroxyl groups, are re- 1quired to provide satisfactory dry time and satisfactory Resins Divisionof the Celanese Coatings Company.

Epi Rex 530 and 530C melt at -l05 C and have weight of 860-1015 perepoxide. Another class of resinous crosslihkers which have been foundespecially suitable are thecopolymers of styrene and allyl alcohol,

obtained from the Shell Chemical Company under the trademark name RP330. This resin has an average of percentage of the isophoronediisocyanate (IFDl). For if the percentage of diisocyanate is reduced byusing a relatively long chain polyol, the finish does not meet theessential resistance to staining by asphalt subplied; the chip time, thetime wherein the chips will adstances.

here to the coating may be varied by using a combination of thesematerials. Examples 4-9 show these effects.

EXAMPLES 4-8 The glaze coat requires between 5 to of free isocyanate ofthe solids thereof. It is found that abrasion resistance appears toincrease as the rubbery nature of the material increases, and abrasionresistance tends to Example 4 5 6 7 8 Chip coat Example 3 Example 3Example 3 Example 3 Example 3 Crosslinking agent None TP-440 RP 330 EpiRel. F.pi Rev. No. l 530 530 Paris crosslinking agent per hundred 3 52.5 L of chip coat Crosslinking agent None RP 330 No. 2 Partscrosslinking 7 q agent per hundred of chip coat Dry time (hours) 7-l IIE 2.3 5.5-(1 2.7 Pot lil't: (min.) x 30-40 -70 Chip time lmin.) 3040-70 40 (iardner Circular Dn-lime Recorder EXAMPLE 9 decrease as thehardness ofthe urethane composition A crosslinking agent for the chipcoat of example 3 is prepared by mixing together Typically, when theabove is mixed with the chip coat of example 3, a dry time of threehours, a chip time of 30 minutes, anda pot life of two hours isobtained.

Another crosslinking agent which may be found satisfactory in reducingdry time while providing adequate chip and pot life is XR-l7, a polymerof a hydroxylfunctional acrylic esters produced by the Rohm and HaasCompany. Also suitable are polyesters based on adipic anhydride, and/orphthalic anhydride and mixtures of polyols such as trimethylol propaneand ethylene glycol which give comparable functionality and equivalence.

Glaze Coat While the intermediate coat follows the chip coat in theapplication of a seamaless floor, it is easier to describe the glazecoat first because the intermediate coat is made from the prepolymerportion of the glaze coat.

Conventional glaze coats operate between these two formulationconstraints: if they are too soft, they are subject to staining; if theyare too hard, they have poor abrasion resistance. We have been able, byusing particular polyester polyol chain extenders-with particular polyolprepolymers-to get both superior stain and abrasion resistance.

While a low isoeyanate content, less than one-third of the weight of theprepolymer and preferably below 25% of the prepolymer is thecharcteristic of the prepolymer in the chip coat, the glaze coatrequires a high increases. The stain resistance, on the other hand, increases with increased crosslinking or with an increase in the hardnessof the urethane coating, but decreases with increase in rubberyproperties or with decreasing crosslinking. The prepolymer used inpreparing the glaze coat therefore has a relatively shorter chain polyolconstituent, i.e. POPT, than has the prepolymer used in the chip coatmaterials. lnstead of having an average equivalent weight in the polyolof 1000 to 2000, as is desirable in a chip coat, in a glaze coat we havefound that the trio] used should have an average equivalent weight ofbetween and 350 or 400, Free (unreacted) NCO should be between 5 and 10%and preferably 6 to 9% or usually about 8% of the solids of the glazecoat. With less than 5% free isoeyanate (based on weight of) on polymersolids, the stain resistance is below bare minimum requirements and withabove 10%, the abrasion resistance may be much too low. Example 10 is apreferred prepolymer.

EXAMPLE 10 A prepolymer is prepared by adding under a blanket of drynitrogen maintained at 160 F. The materials are then cooked at 160 F fora few minutes to 2 hours to complete reaction. Thenare added Dibutyltindilauratc SAG 47 Tinuvin 328 Relative abrasion resistance is measured byholding a sample, i.e. a suitable base coated with a film of thematerial to be tested, against the side of a one gallon jar mill, whichis loaded with a charge of No. 25 grinding media and 1000 grams ofaluminum oxide. The sample is measured at the start and after timedintervals until 30 minutes has elapsed with a portable 60 gloss meter in4 places. The data is plotted and smooth curves are drawn throughthepoints. The percentloss of gloss at 30 minutes is taken as the measureof abrasion loss. A lower value indicates superior abrasion resistance.Clean grinding media and new aluminum oxide are used in each test.

When the prepolymer of example 10 is permitted to moisture cure, thedrying time is about hours and the abrasion loss is -40% at 30 minutes.A conventional 40% solids glaze will lose 75% in the same time. Both toshorten dry time and to improve abrasion resis tance, it is necesary tomix the free-isocyanate terminated prepolymer with a chain extendercomposition.

Wehave found outstanding abrasion resistance combined with stainresistance is obtained by combining the prepolymer with a chain extenderbased on a polycaprolactone trio]. Although a number of polyols improveeither abrasion resistance or drying time, only the combination of thepolycaprolactone trio] and the relatively low equivalent weight POPT inthe polyurethane provides superior abrasion resistance, stainresistances and quick drying. A preferred polycaprolactone trio] chainextender is Example 1].

EXAMPLE 1 1 A chain extender is prepared by mixing the following:

When the chain extender of example 1 1 is twopacked," i.e. mixed, withthe prepolymer of example 10, one volume of chain extender per fourvolumes of prepolymer, and a film formed, the dry time is about 7 hours,the abrasion loss is 2030% at 30 minutes and staining resistance'issatisfactory.

In the above, in place of the PCP-0300, one may substitute equivalentweights of PCP-0301 with substantially equivalent results. Also, we havefound that Multron R-12A may be substituted in whole or in part forequivalent weights of PCP-0300 and obtain reasonably good, althoughsomewhat inferior, results. When Multron R-2, having a high number ofhydroxyls in the mo]- ecule, was substituted, the dry time surprisinglybecame excessive, and when Multron R'-18, having a very high equivalentweight, was substituted, the mix was not compatible, indicating thatpolyesters, if used, should have an equivalent weight of about 200 to600 and about 3 hydroxyls per molecule.

When RP 330 or Epi Rex 530C was substituted in the same manner,extremely poor abrasion resistance resulted. Epi Rex 550 provided betterabrasion resistance but was incompatible. Hydroxyl modified polyacrylateXR17 provided a very rapid dry time and better abrasion resistance thanother hard hydroxyl-containing resins but not so good as the PCP-0300.All of the hard resins improved the resistance to staining by lipstick,however.

Prcpolymers from lPDl/PCP-030O were prepared. That the uniquecombination of polycaprolactone trio] with POPT led to better abrasionresistance than the all-polycaprolactone trio] material is evident fromexamples 1215.

EXAMPLE 12 A prepolymer was prepared, using the method of example 2,fror'nthe following:

Parts lPDl (1.26 m'olcs 2.52 equivalent) 280 Hi Sol 15 U 448 Cellosolveacetate 100 PCP0300 1.52 equivalent) 268 Dibutyltin dilauratc 3.4

Films of the above material, after moisture curing to the tack-freestate, showed an abrasion loss of at 30 minutes. This shows thatPCP-0300 by itself gives poor abrasion resistance.

EXAMPLE 13 EXAMPLE ]4 When the chain extender of example 11 wastwopacked with the prepolymer of example 12 such that the ratio ofNCO/OHwas 1.9, the abrasion loss was 27% at 30 minutes and the dry time was2.5 hours. This shows that the PCP prepolymer two-packed with the PCPproduces a satisfactory glaze.

EXAMPLE 15 When the chain extender of example 11 was twopacked withthe'prepolymer of example 13 such that the ratio of NCO/OH was 2.0, theabrasion loss was 13% at 30 minutes and the dry time was 3.4 hours. Thisshows that the POPT prepolymer prereacted with PCP.

and then two-packed with PCP gives the best abrasion resistance, as wellas excellent dry time.

We have found that in the glaze coatings the ratio of NCO to hydroxyl inthe urethane forming ingredients is very important. The ratio of freeNCO in the prepolymer to -OH in the polyeaprolacetone chain extender(e.g. example 11) must be at least 1.75 to eliminate tackiness in thefloors or laminates produced (unless it is partially prereacted withpolyol).

ln example 10 we use a small percentage of an aliphatic solvent (AshlandSpirits). This is found to reduce the tendency of the high solids glazeto blister by entrapmentofL'U 11 too much of the weak (aliphatic)solvent is used. the polyols needed for crosslinking during the curingstep may precipitate and not react with the free NCO of the prepolymer,weakening the bond. While one hundred percent aromatic solvent causedfrequent blistering, we found that, when about one-fourth of the volumeof solvent is aliphatic, like Ashland Spirits. the solvent mix wassatisfactory. More than one-fourth gave cratcring and syneresis of thepolyol of the mixture.

The cratering or crawling tendency of the glaze, where the film seems toretract at certain points and form a crater, is reduced by incorporatingtherein a spreading agent such, for example, ascellulose-acetatebutyrate in the chain extender.

Also, a U-V absorber is added to reduce ultraviolet degradation andyellowing. The POPT and the IPDI tend to degrade under U-V. This isevidenced by yellowing and loss of abrasion resistance. Such substitutedphenol U-V absorbers as Tinuvin 328 are quite effective.

The Intermediate Coat The intermediate coat is applied to the chips thathave adhered to the chip coat and is designed to penetrate the chips andto harden them, particularly at the high points. The high points canthen be sanded off. To be easily sanded, the material should have poorrather than good abrasion resistance. It is therefore found that,instead of using a polycaprolactone based chain extender such asPCP-0300 or PCP-0301, that one of the polyhydric resinous hardenersshould be used, such as RP 330 or Epi Rez 530. Furthermore, it is foundthat in order to penetrate the chips better, the chain extender part orhardening part of the intermediate coat should be thinned to theneighborhood of 30% solids or so. The intermediate coat is made with thesame or a similar prepolymer as that used in the glaze coat, i.e.example 6. This is mixed with an equal volume of hardener as shown bythe following example. The mixture of 30% solids hardener or chainextender and prepolymer will then be approximately 50% solids.

EXAMPLE 16 Parts Cellosolve acetate 700 RP 330 300 DMP-3() 0.7

Films of the intermediate coat, thus prepared, had a tensile strength of2400 psi, elongation capacity of 100%, a dry time of 4% hours, and wereeasily sanded after 14 hours of drying. In an abrasion test, it lost80-95% of its gloss in 30 minutes.

In the above hardener, the RF 330 may be substituted by other hardpolyhydroxy compounds of resin ous nature, such as Epi Rez 530 orhydroxy polyacrylates having at least 4 hydroxy groups per molecule butan insufficient number to cause gelation prematurely. Cellosolve acetatemay be substituted by other solvents of comparable solubility propertieswith different drying characteristics.

The seamless flooring or seamless laminates produced by the presentinvention have excellent wear resistance. are highly decorative. adherehighly to substratcs such as cement, even low-grade cement, and greatlydecrease maintenance cost of buildings. They do not require waxing, asdo most other types of floor ing, and are now solving a substantialdemand in the marketplace.

The definitions of the ingredients previously mentioned are shown in thefollowing appendix.

It is to be understood that variations and modifications of the specificproducts and processes herein shown and described for purposes ofillustration may be made without departing from the spirit of theinvention.

EXAMPLE 17 A coating for vinyl asbestos tile which eliminates the needfor waxing is applied as follows: The tile iseleaned with a good waxstripper until the surface is water break free. It is then allowed todry. After it is dry, the prepolymer of Example 1 l is mixed with thehardener of Example 16 in equal volumes. It is applied to the surfacewith a foam roller at a rate of about 400 sq. ft./gallon. It is allowedto dry for 3-5 hours.

Four volumes of the prepolymer of Example 1 l are then mixed with onepart of the prepolymer of Example 12. It is applied to the surface at arate of 400 sq. ft./gallon. After overnight dry, it is ready fortraffic.

EXAMPLE 18 A seamless flooring is applied as follows: The surface iscleaned, all cracks are filled, and it is allowed to dry. Part A ofExample 1 is mixed with an equal volume of Part B of Example 1. It isapplied to the surface with a trowel or roller and allowed to dry for 2hours.

Then, four volumes of the chip coat of Example 2 are mixed with one partof the hardener of Example 3 and applied to the surface with a trowel orroller at a rate of sq. ft./gallon. Chips are broadcast into the surfacewithin 30 minutes. The surface is allowed to cure for 3 hours. Equalvolume of the prepolymer of Exampie 10 is then mixed with one volume ofthe hardener of Example 16 and applied by roller or trowel, to thechipped surfaces at a rate of 180 sq. ftJgallon. It is allowed to dryovernight and then sanded vigorously, and vacuumed clean. Four volumesof the prepolymer of Example 10 is mixed with one volume of the chainextender of Example 11 and allowed to dry for 6 hours after which asecond coat of the same glaze can be applied. If a second coat is notnecessary, the floor can be opened to traffic the following morning.

EXAMPLE 19 The chip coat of Example 18 is replaced witih a second coatof the epoxy emulsion of Example 1 and chips are broadcast into it.

APPENDIX I Glossary of Raw Materials Ashland Spirits Ashland ChemicalCompany.

a mineral spirits of boiling range, initial 310 F, 50% 341 F, end points396 F; kauri butanol value 36.5;

containing 10.1% aromatics and 1.0% olefins.

Cellosolve Acetate Union Carbide Corporation brand of ethylene glycolmonoethyl ether acetate.

Dccfo 97-2 Ultra Adheisives lne.

latex paint antifoamer. IMF-30 Rohm and Haas Company. I 7

brand of 1,3,5-tris (dimethylamino) phenol. ,1 EAB 551-0.2 EastmanChemical Products, Inca cellulose acetate butyrate containing 53%butyryl.

1.6% acetyl,

1.7% hydroxyl and having avis cosity by ASTM 550 melting point 145l5 Cgqoo-fnooo ei m per epoxidc.

Epi Rez WDSlO Celanese Resins, Div. of Celanese Coatings Company. Q I Vdiglycidyl ether of Bisphenol persing in water.

A formulated for dis- Ferro No. 820 Ferro Corporation brand ofdibutyltin dilaurate. HA-SlO Wyandott Chemicals Corportion Pluradot HA-Sl0 polyol. POPT (90%) triol capped with ethylene oxide of 1500equivalent weight. Ni-Sol l5 Ashland Chemical Company. w

an aromatic naphtha of boiling range, initial 360F, 50%--372F, end point410F; kauri butanol value 93. Humble Oil and Refining Company Solvesso150 can be used interchangeably with l-li-Sol l5. lgepal CO-610 GAFCorporation brand of nonylphenoxypoly (ethyleneoxy) ethanol. lPDlVeba-Chemie AG.

isophorone diisocyanate. Y LHT-240, -42, -ll2 Union Carbide CorporationNiax polyol. I POPT's of equivalent weight: LHT-240, 240; LHT- 240, 240;LHT-42, 1385; LTl-l-l 12, 500. MFA-60 Baker Castor Oil.

castor oil derivative used to aid pigment wetting. Multron R-2, R-l2A,R-l8 Mobay Chemical Company. v saturated polyesters of equivalentweight: R-2, 140;

R-l2A, 335; R48, 935. approximate hydroxyl per molecule: R-2, high; R-

12A, slightly more than 3; R-l8, slightly more than 2. PCP-0300, -030l,-03l0 Union Carbide Corporation Niax polyol. polycaprolactone triols ofequivalent weight: PCP- 0300, 180; PCP-0301; 100; PCP-0310, 300.Pluracol 220 Wyandotte Chemicals Corporation.

POPT of 2070 equivalent weight capped ethylene oxide. Polymeg 1000, 2000The Quaker Oats Company.

polyether diols from tetrahydrofuran of equivalent weight: Polymeg 1000,500; Polymeg 2000, 1000. POPT abbreviation for polyoxypropylcne triol.7R05 asbestos fiber C. P. Hall Company R900 TiO E. l. du Pont de Nemours8t Company,

Inc. Ti-Purc R-900 grade of rutile titanium dioxide.

a copolymer of styrene and allyl alcohol of equivalent .weight3(l0andmolecular weight 1600, with an av- 5 eragc-of'5.3 hydroxyl groupspermoleculc.

50%, 320F dry point, 344F; kauri butanol value,

92; mixed aniline, 56F; containing l.l% paraffins,

98.9% aromatics. Y Solvesso 150 see Hi-Sol l5. Tide Procter & Gamblelaundry detergent.

Tinuvin 328- Geigy Industrial Chemicals.

an ultra-violet absorber of the beniotriazolesubstituted phenol family.TP-4'40, TP-740 Wyandotte Chemicals'Corporation Pluracol polyols. POPTsderived from trimethylolpropane with equivalent weights; TP-440, 140;TP-740,240. Versamid 5501 General Mills Chemicals, lnc.

a polyamide resin co-reactive with epoxy resins. No. 1 White Thompson,Weinman & Company.

grade of natural ground calcium carbonate. XR-l7 Rohm and Haas Company.

isobutyl acetate solution of a hydroxyl-functional acrylic resin with asolution equivalent weight of 1760.

We claim: v g l. A method for providing an adherent wearresistant,decorative layeron a substrate having a substantially hardened sealantlayer of liquid epoxy resin, said method comprising (1) applying on saidsealant layer a polyurethane base chip coat, said chip coat comprising asolution in organic solvent of (A) an -NCO terminated prepolymer of adiisocyanate containing unequally reactive isocyanate groups and abranched chain polyol having an average equivalent ing of a solution ofpolyurethane comprising: (a) an -NCO terminated prepolymer of adiisocyanate containing unequally reactive isocyanate groups and abranched chain polyol having an average equivalent weight of from 180 to400, wherein said prepolymer has a free NCO content of from 1.5 to 6%and (b) a solid, soluble hydroxyl containing resin having at least 4hydroxyl groups per molecule to react with said NCO groups of saidprepolymer, (5) after permitting said intermediate coat to hardenapplying over the hardened surface a glaze coat which comprises asolution of: (i) an NCO terminated prepolymer of a diisocyanatecontaining unequally reactive isocyanate groups and a branch chainpolyol having an equivalent weight of between 160 and 400 and a free NCOcontent of 5 to 10% and (ii) a chain extender comprising apolycaprolactone troil, a polyester having an equiva- RF 330 ShellChemical Company Rcsinous Polyol ing over the solidified chip coat anintermediate coat.

lent weight of about 200 to 600 and about 3 hydroxyls per molecule ormixtures thereof. to react with said free NCO.

2. The method of claim 1 wherein said chip coat has at least a 60%polymer solids content and contains a viscosity stabilizer and apigment.

3. The method of claim 1 wherein the solid resin, having at least 4hydroxyl groups per molecule. is selected from the groups consisting ofsoluble epoxy resins, the copolymers of allyl alcohol with a styrene.and polymers of hydroxyl alkly acrylates.

4. The process of claim 1 wherein said intermediate coat contains ahardener selected from the group consisting of copolymers of allylalcohol and a styrene, epoxy resins, and polymers of hydroxy alkylacrylates.

5. The process of claim 1 wherein said glaze coat has at least a 55%polymer solids content.

6. The process of claim 5 wherein the glaze coat is a solution in mixedaromatic and aliphatic solvent.

7. The process of claim 6 wherein the glaze coat contains a spreadingagent.

8. The process of claim 7 wherein the spreading agent iscelluloseacetate-butyrate.

9. The process of claim 8 wherein said glaze coat contains a U-Vstabilizer.

10. The process of claim 1 wherein the diisocyanate is isophoranediisocyanate and the polyol is a polyoxypropylene triol 11. The processof claim I, wherein the chain extender is polycaprolactone triol and theratio of equivalents of free NCO in said glaze coat prepolymer toequivalents of OH in said polycoprolactonc is at least 12. The processof claim I, wherein the equivalent weight of diisocyanatc in the chipcoat is from about 1.5 to 2.5 times that of the equivalent weight of thepolyol.

13. The process of claim 1, wherein the solid soluble hydroxylcontaining resin is an epoxy resin prepared from Bisphenol A and anepichlorohydrin having 4 to 6 hydroxyl groups per molecule.

14. The process of claim 11, wherein the diisocyanate is isophoronediisocyanate and the polyol is polyoxypropylene triol.

1. A METHOD FOR PROVIDING AN ADHERENT WEAR-RESISTANT, DECORATIVE LAYERON A SUBSTRATE HAVING A SUBSTANTIALLY HARDENED SEALANT LAYER OF LIQUIDEPOXY RESIN, SAID METHOD COMPRISING (1) APPLYING ON SAID SEALANT LAYER APOLYURETHANE BASE CHIP COAT, SAID CHIP COAT COMPRISING A SOLUTION INORGANIC SOLVENT OF (A) AN -NCO TERMINATED PREPOLYMER OF A DIISOCYNATECONTAINING UNEQUALLY REACTIVE ISOCYNATE GROUPS AND A BRANCHED CHAINPOLYOL HAVING AN AVERAGE EQUIVALENT WEIGHT OF FROM 1000 TO 2000, SAIDPREPOLYMER HAVING FREE -NCO CONTENT OF FROM 1,5 TO 6% AND AS A CROSSLINKING AGENT (B) A SOLID RESIN HAVING AT LEAST 4 HDYROXYL GROUPS PERMOLECULE, (2) INCORPORATING COLORED PAINT CHIP INTO THE SURFACE REGIONSOF SAID CHIP COAT AFTER ITS APPLICATION OVER SAID SEALANT COAT ON SAIDSEALANT LAYER, BUT BEFORE IT IS PERMITED TO HARDERN, (3) PERMITTING SAIDCHIP COAT WITH CHIPS THEREIN TO SOLIDIFY, (4) APPLYING OVER THE SOLIFIEDCHIP COAT AN INTERMEDIATE COATING OF A SOLUTION OF POLYURETHANECOMPRISING: (A) AN -NCO TERMINATED PREPOLYMER OF A DIISOCYANATECONTAINING UNEQUALLY REACTIVE ISOCYANATE GROUPS AND A BRANCHED CHAINPOLYOL HAVING AN AVERAGE EQUIVALENT WEGHT OF FROM 180 TO 400, WHEREINSAID PREPOLYMER HAS A FREE -NCO CONTENT OF FROM 1,5 TO 6% AND (B) ASOLID, SOLUBLE HYDROXYL CONTAINING RESIN HAVING AT LEAST 4 HYDROXYLGROUPS PER MOLECULE TO REACT WITH SAID -NCO GROUPS OF SAID PREPOLYMER,(5) AFTER PERMITTING SAID INTERMEDIATE COAT TO HARDEN APPLYING OVER THEHARDENED SURFACE A GLAZE COAT WHICH COMPRISES A SOLUTION OF: (I) AN -NCOTERMINATED PREPOLYMER OF A DIISOCYNATE CONTAINING UNEQUALLY REACTIVEISOCYANATE GROUPS AND A BRANCH CHAIN POLYOL HAVING AN EQUIVALENT WEIGHTOF BETWEEN 160 AND 400 AND A FREE -NCO CONTENT OF 5 TO 10% AND (II) ACHAIN EXTENDER COMPRISING A POLYCAPROLACTONE TROIL, A POLYESTER HAVINGAN EQUIVALENT WEIGHT OF ABOUT 200 TO 600 AND ABOUT 3 HYDROXYLS PERMOLECULE OR MIXTURE THEREOF, TO REACT WITH SAID FREE -NCO.
 2. The methodof claim 1 wherein said chip coat has at least a 60% polymer solidscontent and contains a viscosity stabilizer and a pigment.
 3. The methodof claim 1 wherein the solid resin, having at least 4 hydroxyl groupsper molecule, is selected from the groups consisting of soluble epoxyresins, the copolymers of allyl alcohol with a styrene, and polymers ofhydroxyl alkly acrylates.
 4. The process of claim 1 wherein saidintermediate coat contains a hardener selected from the group consistingof copolymers of allyl alcohol and a styrene, epoxy resins, and polymersof hydroxy alkyl acrylates.
 5. The process of claim 1 wherein said glazecoat has at least a 55% polymer solids content.
 6. The process of claim5 wherein the glaze coat is a solution in mixed aromatic and aliphaticsolvent.
 7. The process of claim 6 wherein the glaze coat contains aspreading agent.
 8. The process of claim 7 wherein the spreading agentis celluloseacetate-butyrate.
 9. The process of claim 8 wherein saidglaze coat contains a U-V stabilizer.
 10. The process of claim 1 whereinthe diisocyanate is isophorane diisocyanate and the polyol is apolyoxypropylene triol
 11. The process of claim 1, wherein the chainextender is polycaprolactone triol and the ratio of equivalents of free-NCO in said glaze coat prepolymer to equivalents of -OH in saidpolycoprolactone is at least 1.75.
 12. The process of claim 1, whereinthe equivalent weight of diisocyanate in the chip coat is from about 1.5to 2.5 times that of the equivalent weight of the polyol.
 13. Theprocess of claim 1, wherein the solid soluble hydroxyl containing resinis an epoxy resin prepared from Bisphenol A and an epichlorohydrinhaving 4 to 6 hydroxyl groups per molecule.
 14. The process of claim 11,wherein the diisocyanate is isophorone diisocyanate and the polyol ispolyoxypropylene triol.